ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
611 
isms. Thus, the htemoglobins of different animals are different, and as 
the lirematin is the same, the difference must be in the albuminoid sub- 
stance. Differences in the products of metabolism are illustrated by 
the bile and the fat in different animals. So cynuric acid is only fouud 
in the dog, thiosulphuric acid in dog and cat. Different reactions to 
morphin, toxins, &c., are well known. From such evidence the author 
concludes that each species is characterised by chemical peculiarities, 
especially in its albuminoids. 
Pigmentation of Salamander.- — Dr. A. Fischel begins an interest- 
ing paper by relating how Prof. Rabl and he divided a collection of 
larval salamanders (S. maculata), the professor placing his set in running 
water, while the author kept his in porcelain dishes and gave them fresh 
water several times a day. Those in the running water acquired the 
usual dark coloration, while those in the dishes were predominantly 
light yellow. The details of the differences are stated ; thus the gills 
of the first set were brownish-black, while those of the second set had a 
minimum of pigment, and therefore showed the red colour of the blood. 
An inquiry into the causes of difference led to the conclusion that 
temperature was an important factor. In the running water it was 
6°-7° C., or less on cold days ; in the dishes it was 15°-18° C., i.e. about 
three times as much. This was experimentally confirmed by placing 
dark larvae in warmed running water. They became gradually lighter, 
to a degree varying with the age of the larvae at the commencement of 
the experiment. Thus newly born larvae became very light in colour ; 
but the susceptibility to external influence decreased with age. The 
converse experiment of making the larvae darker by cooling the water 
also succeeded. But, as before, the result was more or less marked 
according as the larvae had been for a short time or for a long time pre- 
viously subjected to conditions with an influence opposite to that of the 
experiment. In other words, the effects of cold or warmth tend to 
become fixed. The light-coloured larvae were in no way pathological, 
in fact, their vigour was rather above the average. 
Previous investigators of the effect of external conditions on colora- 
tion have dealt mainly with adults. But L. Hermann showed that frog 
tadpoles reared in the dark became lighter, and that they became darker 
again when subjected to light. The author found that the same was 
true, but to a less degree, of his salamanders. He notes, at this point in 
his paper, a few previously recorded facts to the effect that warmth 
tends to lighter coloration. 
As i§ well known, pigment occurs in three ways in the skin of the 
salamander larva : — (1) As minute brownish-black spherules in the epi- 
thelial cells ; (2) in branched pigment-cells whose processes pass between 
the epithelial cells : and (3) most of all, in the ramified pigment-cells of 
the cutis. In the light larv?e there is very little pigment in the epithelial 
cells, and it is usually confined to the periphery ; the pigment-cells of 
both kinds are almost spherical and without processes. Not only is the 
pigment concentrated, but the whole cell is contracted and all the pro- 
cesses are drawn in. This is true even of the visceral pigment-cells. 
Moreover, in the light larv®, the pigment-cells with light yellow 
♦ Arch. f. Mikr. Anat., xlvii. (1896) pp. 719-48 (1 pi.). 
